1. Field of the Invention
The present invention relates to an image forming apparatus such as a color laser printer.
2. Background Art
As an electrophotographic color laser printer, a so-called tandem color laser printer is known where process units including toner boxes, developer rollers and photosensitive drums are plurally disposed in correspondence to toners of the respective colors of yellow, magenta, cyan and black.
In this tandem color laser printer, toners of the respective colors accommodated in the toner boxes are supplied to the photosensitive drums by the developer rollers in the process units so that toner images of the respective colors are formed at substantially the same time on the photosensitive drums. Thus, color images can be formed at substantially the same speed as in a monochrome laser printer.
In this tandem color laser printer, as described for example in JP-A-2002-72602, the toner box, the developer roller and the photosensitive drum are integrally disposed in each process unit, and each process unit is replaced when the toner box runs out of toner.